Abstract:
Following the serious grasshopper outbreaks of 1986, a pilot program was defined between the U.S. Geological Survey and the U.S. Agency for International Development. The primary goal of this program was to develop, test, and evaluate a near-real time monitoring procedure by using satellite remote-sensing and geographic-information-system technologies in support of grasshopper control programs ... in West Africa. Inherent in this goal was the need to design and present information for acceptance and use by decision makers and agents responsible for grasshopper control. The underlying philosophy was to develop techniques and capacities that could be transferred to African institutions. The initial design and production of vegetation index image maps occurred in 1987. The image maps were derived from satellite data collected by the AVHRR sensor on the NOAA series of polar-orbiting satellites. The NOAA series of satellites was selected rather than other Earth-imaging satellites because of the requirement for producing relatively low resolution/low data volume/low cost products that were of sufficient detail for landscape feature interpretations. Other requirements included the need for high temporal frequency imagery to minimize the effects of cloud cover, for spatially synoptic data sets for national coverage, and for near-real time availability of data. Maps of vegetation greenness were produced by registering and merging AVHRR LAC-derived normalized difference vegetation index (NDVI) data with cartographic data in a geographic information system. The maps, each representing maximum NDVI value composites for 14-day periods, were produced during the rainy seasons for a number of Sahelian and Northwest African countries. Grasshopper and locust control teams used the maps for planning and conducting field and aerial surveys to more efficiently locate areas of infestation. African governments and regional African organizations expressed a strong interest in the continued need for greenness information for detailed and timely monitoring of vegetation conditions. One of the major goals of the program was to transfer the technology and capability of producing satellite derived vegetation index products to an African institution. As a result, the scheduled phase out of the African greenness mapping program at the EROS Data Center in 1989 and 1990 was coordinated with a major effort to transfer the technology to Africa. The regional AGRHYMET Center was identified as the appropriate organization for this process. AGRHYMET serves nine West African countries by providing timely, reliable data on agricultural, meteorological, and hydrological conditions. As of May 1, 1990, greenness map production at AGRHYMET has been in an operational mode. The regional AGRHYMET Center's address is as follows:

Description:
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Quality
The satellite data were recorded by NOAA-9 and NOAA-11 satellites and transmitted to the National Climatic Data Center in Washington, D.C. Approximately three scenes per week were acquired for most of northern Africa. The satellite data were sent to the EROS Data Center where each scene was entered into the AVHRR Data Reception and Processing System (ADAPS) and previewed for cloud cover and to determine whether a country of interest was covered by the near nadir (central) portion of the scene. Scenes that passed this initial screening were processed further by ADAPS.